1. Field of the Invention
The present invention relates to convenience copiers and document feeders. More specifically, the invention relates to such copiers having duplex capabilities and to collating document feeders than invert the document automatically for producing duplex collated copies without a sorter.
2. Brief Description of the Prior Art
It is well known in the prior art to provide convenience copiers with duplex capabilities, with document feeders that circulate the document in a manner suitable for producing collated copies, or with document inverters that present both sides of the document for copying. Examples include: 1) in relation to the first feature -- U.S. Pat. Nos. 3,318,212; 3,536,398; 3,615,129; 3,630,607; 3,645,615, 3,671,118; 3,672,765; 3,687,541; 3,697,171; 3,775,102; 3,844,653; 3,856,295; 3,862,802; 3,866,904; 3,869,202; 2) in relation to the second feature -- U.S. Pat. Nos. RE 27,976; 3,552,739; 3,556,511; 3,709,595; 3) and, in relation to the third feature -- U.S. Pat. Nos. 3,227,444; 3,416,791 and 3,675,999.
It also is known in the prior art to combine certain of the above mentioned features in a unified structure or control. U.S. Pat. No. 3,630,607 is notable for its disclosure of a collating feeder on a convenience copier having duplex capabilities. U.S. Pat. No. 3,844,653 discloses a convenience copier having duplex capabilities with a document inverting mechanism. U.S. Patent No. 3,862,802 discloses a duplex copier with a document inverting mechanism, and is said to be useable with a sorter to produce collated copies. "Research Disclosure" Vol. 133, No. 13329, May 1975, describes a manual approach for producing collated duplex copies without a sorter.
It is clear from such disclosures that numerous rather sophisticated features have been developed for modern copiers to supplement their basic copying function. This is not surprising when the economics of the total copying operation are considered. What is surprising is that, in spite of a clear-cut need, no one has succeeded in developing a fully automatic duplex copier that is capable of handling two-sided originals and also is conducive to finishing operations, such as collating, stapling and off-set stacking, or is not burdened by a sorter. Typically, prior art structures that approach such capabilities will not handle two sided originals on a fully automatic basis, or have required a cumbersome and expensive sorter than still leaves the stapling and off-set stacking to manual or very complex automatic operations.